The present invention relates to a cooling system for an engine powered non-rail off-road work vehicle such as an agricultural tractor.
In conventional vehicle cooling systems heat exchangers are arranged in series. This requires the air to pass through all the heat exchangers to meet an individual cooler's needs. This arrangement, which typically uses a mechanically driven fan to pull the air through the heat exchangers, also limits the area through which the air must pass. This is inefficient.
An advance vehicle cooling system, such as an agricultural tractor having an engine with a horizontally oriented rotation axis and a hood covering the engine is described in U.S. patent application Ser. No. 10/617,612 filed 11 Jul. 2003 and assigned to applicant's assignee. This cooling system includes an engine cooling radiator positioned above the engine and between the engine and the hood and a fan unit with electric motor-driven fans blowing air upwardly through the radiator. The fan unit is positioned above the engine and between the engine and the radiator. An engine charge air cooler is also positioned above the engine and between the engine and the hood, and a charge air cooler fan unit has electric motor-driven fans which blow air upwardly through the cooler. The hood has openings in its upper surface through which passes air blown by the radiator fan unit and the charge air cooler fan unit. This cooling system blows heated cooling air vertically upwardly, thus preventing the heated cooling air from being drawn back into the intakes of the cooling system and preventing heated air from being blown onto the exterior of the tractor cab.
However, in this system the air inlets and outlets are close enough together that they can compete for common air, thus causing control problems. Cooling air for the forward cooling components can flow over surfaces where it may be heated prior to entering the heat exchanger. Also, not all heated air is exhausted vertically, because the oil cooler and AC condenser are mounted behind the engine so that the heated air from these units is discharged laterally.
Vehicle cooling systems must be increasingly flexible and efficient while remaining cost competitive. Such systems should reduce recirculation, reduce fan power consumption, reduce or eliminate mechanical ties to the engine, and provide improved control capability.